Fourth-Generation Metatarsal Extra-Capsular Transverse Akin (META) Osteotomies for Percutaneous Hallux Valgus Correction: A Series of 729 Consecutive Feet

Category: Bunion; Lesser Toes Introduction/Purpose: Fourth-generation percutaneous or minimally invasive hallux valgus surgery utilises a transverse osteotomy to achieve deformity correction. There are only a small number of series reporting the clinical and radiological outcomes of transverse osteotomies, many of which have methodological limitations such as small sample size, limited radiographic follow up or use of non-validated outcome measures. The aim of this study was to provide a methodological robust investigation into percutaneous transverse osteotomies for hallux valgus deformity. Methods: A prospective case series of consecutive patients undergoing fourth generation metatarsal extra-capsular transverse osteotomy (META) performed by a single surgeon (PL) between November 2017 and January 2023. The primary outcomes were radiographic deformity correction and clinical foot function assessed using the Manchester-Oxford Foot questionnaire (MOXFQ-a validated patient reported outcome measure). Radiographic deformity (Hallux valgus angle (HVA) and 1-2 Intermetatarsal angle(IMA), sesamoid position) was assessed according to AOFAS guidelines. Secondary outcomes included Visual Analogue Scale for Pain and radiographic deformity recurrence (defined as HVA >20° at final radiographic follow up). All p-values < 0.05 were considered significant. Results: 729 feet from 483 patients (456 Female, 27 Male, mean age 57.9±11.9 years) underwent META. Radiographic data (minimum 12 months post-surgery) was available for all feet with mean follow up of 2.6±1.3 years (range 1.0-5.7). There was a statistically significant improvement (p< 0.05) in both HVA; 29.5±8.5° to 7.3±6.7°, and IMA, 12.9±3.4° to 4.6±2.5°. All MOXFQ domains showed significant improvement (p< 0.05); Index 36.6±19.1 to 11.8±13.8, Pain 40.1±22.1 to 15.6±16.4, Walking/Standing 32.2±23.2 to 10.2±15.8 and Social Interaction 40.0±20.6 to 9.7±14.0. The recurrence rate was 4.6% (n=33) with a significantly higher proportion of sesamoids in Grade 2 and 3 in the recurrence group (p< 0.05). There was 1 non-union, 1 deep infection and 20 cases of superficial infection. No avascular necrosis of the first metatarsal head occurred. Conclusion: This is the largest consecutive series of any percutaneous osteotomy technique to correct hallux valgus deformity. This study demonstrates that the technique leads to significant improvement in clinical and radiographic outcomes with a low rate of recurrence. Recurrence may be linked to incomplete sesamoid reduction at the time of surgery.